8o POTASSIUM BROMIDE POTASSIUM BITARTRATE (Cream of Tartar) KC4HB06 = 188-2 The impure salt constitutes crude tartar (sec p. 36). The pure or refined product forms white rhombic crystals or crystalline powder and dissolves in about 220 parts of cold water or 15 parts of boiling water, but is insoluble in alcohol. It may be contaminated with small proportions of calcium, lead, copper or iron salts, or adulterated with various mineral salts (alum or other acid salt). Its analysis includes the following : 1. Insoluble Substances, -i gram is either treated with 220 e.e. of water at the ordinary temperature or boiled with 18 e.e. of water. If the salt is pure, a clear solution should be obtained in either ease ; any insoluble, residue left is tested especially for calcium tartrate, calcium carbonate, gypsum, clay, etc. 2. Nitrates, Sulphates, Chlorides............10 grams are heated to boiling with 30 c.c. of water, cooled and filtered, the nitrate being tested with the ordinary reagents for these radicles. 3. Heavy Metals,.........5 grams are dissolved in ammonia, the liquid being acidified with hydrocllloric acid and treated with hydrogen sulphide, then with ammonium sulphide, etc., according to the ordinary method of analysis-:. 4. Calcium Tartrate (small quantities)......-I gram is treated in the. hot with 10 c.c. of water and a. lew drops of ammonia, until solution occurs : ammonium oxalate should give no turbidity. 5. Quantitative Determination.......-o'5 gram is dissolved in boiling water (100 c.c.) and titrated with normal alkali in presence of pheuolphtha- lein, i c.c, N-alkali = 0-1882 gram of pota.ssinm bitartrate. POTASSIUM BROMIDE KBr i ic) White, deliquescent crystals, highly soluble in water. It may be con- taminated by broniates, sulphates, chlorides, iodides and carbonates. The tests and determinations made are as follows : 1. Sulphates, Metals, Alkaline Earths." 'The i : 10 solution is tested with barium nitrate (sulphates), hydrogen sulphide (heavy metals), ammonia, ammonium sulphide and ammonium oxalate. Sodium is detected by the flame test or by potassium pyroantimoniate. 2. Carbonates.-No effervescence should be obtained with dilute hydrocllloric acid. A crystal placed on red litmus paper and moistened with a drop of water gives a blue stain if alkali carbonate is present. 3. Bromates.o-i gram, moistened with very dilute sulphuric acid, should not turn yellow or emit an odour of bromine. 4. Iodides.-0-5 gram, dissolved in 5 c.c. of water, is treated with a drop of ferric chloride solution or a few crystals of potassium nitrite and arric oxide, this gives the total iron (i part Fea03 0-7 part Fe).